Multi-electrode arrangement for therapy

Abstract

In some examples, a system includes one or more leads including a plurality of electrodes, where the one or more leads are configured to position the plurality of electrodes in a plurality of extracardiac locations to deliver cardiac pacing to a right atrium (RA), a right ventricle (RV), a left atrium (LA), and / or a left ventricle (LV) of a heart of a patient. The system may also include an implantable medical device (IMD) coupled to the one or more leads. The IMD device may be configured to deliver the cardiac pacing via the plurality of electrodes.

Description

[0001] This application claims the benefit of U.S. Provisional Patent Application Serial No. 63 / 381,377, filed Oct. 28, 2022, the entire content of which is incorporated herein by reference. TECHNICAL FIELD

[0002] This application relates to cardiac sensing and therapy and, more particularly, to configurations of implantable systems for improving defibrillation, sensing, and / or pacing capabilities in extracardiac applications. BACKGROUND ART

[0003] Implantable systems such as pacemakers with or without cardioversion or defibrillation capabilities can treat cardiac dysfunctions such as bradycardia, tachycardia, and heart failure. Such implantable systems can include electrical devices configured to deliver therapy via electrodes, which are typically carried by one or more implantable medical leads. Treatment of tachycardia can include shock and / or anti-tachycardia pacing (ATP). Implantable systems can also be configured to deliver cardiac pacing to, for example, treat bradyarrhythmias or for cardiac resynchronization therapy (CRT).

[0004] Delivering CRT to improve cardiac electro-mechanical function. CRT can help enhance cardiac output by resynchronizing the electro-mechanical activity of the ventricles. CRT typically includes delivering pacing to one or two ventricles via endocardial leads to synchronize their contractions. Ventricular dyssynchrony can occur in patients with congestive heart failure (CHF).

[0005] Due to the inherent surgical risks of directly attaching and replacing implantable medical leads within or on the heart, subcutaneous implantable systems have been designed where the implantable system and leads are subcutaneous, outside the thoracic cavity. It has also been proposed that the distal portion of the leads of an implantable system can be implanted within the thoracic cavity, e.g., sub-sternally.

[0006] Implantable medical leads are also used to monitor and / or deliver therapy to tissues other than the heart. Implantable medical leads can be used to position one or more electrodes within or near a target nerve, muscle, or organ to deliver electrical stimulation to such tissues. Implantable medical leads can be used to position one or more sensors within or near a target tissue to monitor biological signals from such tissues. As an example, an implantable medical lead can be positioned in the epidural space to deliver spinal stimulation, or near other nerves such as pelvic nerves or renal nerves to deliver nerve stimulation to the nerves. SUMMARY OF THE INVENTION

[0007] Electrical stimulation therapy using epicardial leads includes delivering electrical pulses via electrodes on the leads to a given chamber of the heart. This disclosure describes an implantable medical system that may include an implantable epicardial lead having electrodes configured to sense and pace multiple regions of the heart. Epicardial locations for lead placement may include extravascular locations (i.e., outside of a vessel and / or vasculature) and / or locations within epicardial blood vessels within the thoracic cavity (e.g., including but not limited to the internal thoracic vein (ITV), intercostal veins, superior epigastric vein, azygos vein, hemiazygos vein, and accessory hemiazygos vein). For example, this disclosure describes leads configured to deliver cardiac pacing to the right atrium (RA), right ventricle (RV), left atrium (LA), and / or left ventricle (LV) of a patient's heart by placing the lead in a corresponding extravascular region or within an epicardial blood vessel (e.g., both anterior and posterior to the heart). In this manner, cardiac resynchronization therapy (CRT) can be achieved by capturing the RA, RV, and LV. CRT can also be achieved by capturing the LA, LV, and RV.

[0008] Although described primarily in the context of implantable medical devices having one or more leads, the techniques of this disclosure can be applied using leadless pacing devices. Leadless pacing devices can also be placed in various epicardial regions to facilitate capture and / or sensing of the RA, RV, and LV. Leadless pacing devices can be used alone or in combination with devices having one or more leads. This disclosure discusses the context of ICD systems as well as systems other than ICD systems, including but not limited to bradycardia or cardiac resynchronization therapy (CRT) pacemaker systems that may not be configured to deliver antitachycardia shocks.

[0009] In one example, a system includes one or more leads and an implantable medical device (IMD) coupled to the one or more leads. The one or more leads include multiple electrodes. The one or more leads are configured to position the multiple electrodes in multiple epicardial locations to deliver cardiac pacing to the right atrium (RA), right ventricle (RV), and left ventricle (LV) of a patient's heart. The IMD device is configured to deliver the cardiac pacing via the multiple electrodes.

[0010] In another example, a system includes one or more leads, an implantable medical device (IMD) coupled to the one or more leads, and one or more leadless pacing devices. The one or more leads include multiple electrodes. The one or more leads are configured to position the multiple electrodes at multiple epicardial locations to deliver cardiac pacing to a first subset of the right atrium (RA), right ventricle (RV), and left ventricle (LV) of a patient's heart. The IMD device is configured to deliver the cardiac pacing via the multiple electrodes. The one or more leadless pacing devices can be configured to deliver cardiac pacing to a second subset of the RA, RV, and LV.

[0011] In another example, a method includes positioning a plurality of electrodes via one or more leads that include the plurality of electrodes to deliver cardiac pacing to a right atrium (RA), a right ventricle (RV), and a left ventricle (LV) of a patient's heart. The method further includes delivering cardiac pacing to the RA, the RV, and the LV of the patient's heart via an implantable medical device (IMD) coupled to the one or more leads via the plurality of electrodes positioned at a plurality of extra-cardiac locations via the one or more leads.

[0012] In another example, a method includes positioning a plurality of electrodes via one or more leads that include the plurality of electrodes to deliver cardiac pacing to a first subset of a right atrium (RA), a right ventricle (RV), and a left ventricle (LV) of a patient's heart. The method further includes delivering cardiac pacing to the first subset of the RA, the RV, and the LV of the patient's heart via an implantable medical device (IMD) coupled to the one or more leads via the plurality of electrodes positioned at a plurality of extra-cardiac locations. The method further includes delivering cardiac pacing to a second subset of the RA, the RV, and the LV of the patient's heart via one or more leadless pacing devices.

[0013] In another example, a system includes a plurality of pacing devices configured to be positioned at a plurality of extra-cardiac locations. The plurality of leadless pacing devices are configured to pace a right atrium (RA), a right ventricle (RV), or a left ventricle (LV) of a patient's heart or any combination thereof.

[0014] In another example, a system includes one or more extra-cardiac leads that include a plurality of electrodes. The one or more leads include a first extra-cardiac lead configured to position a first subset of the plurality of electrodes to deliver cardiac pacing to a right atrium (RA) and a right ventricle (RV) of a patient's heart. The one or more leads include a second extra-cardiac lead configured to position a second subset of the plurality of electrodes to deliver cardiac pacing to a left ventricle (LV). The plurality of electrodes include a plurality of electrodes configured to deliver cardiac pacing. The one or more leads include one or more electrodes configured to deliver anti-tachycardia shocks. The system includes an implantable medical device (IMD) coupled to the one or more leads. The IMD is configured to deliver the cardiac pacing via the plurality of electrodes configured to deliver cardiac pacing and to deliver the anti-tachycardia shock via the one or more electrodes configured to deliver anti-tachycardia shocks. The first lead is configured to be positioned anteriorly relative to the patient's heart, and the second lead is configured to be positioned posteriorly relative to the patient's heart.

[0015] The present invention content aims to provide an overview of the subject matter described in this disclosure. It is not intended to provide an exclusive or exhaustive explanation of the systems, devices, and methods described in detail within the accompanying drawings and the following description. Further details of one or more examples are set forth in the following drawings and description. Other features, objects, and advantages will be apparent from the description, the drawings, and the statements provided hereinafter. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] Figure 1 is a conceptual diagram showing a front view of a patient implanted with an exemplary extracardiac implantable medical device system.

[0017] Figure 2 is a conceptual diagram showing a side view of a patient implanted with an exemplary extracardiac implantable medical device system.

[0018] Figure 3 is a conceptual diagram showing a transverse view of a patient implanted with an exemplary extracardiac implantable medical device system.

[0019] Figure 4 is a functional block diagram of an exemplary configuration of electronic components of an exemplary IMD.

[0020] Figure 5 is a conceptual diagram showing a front view of a patient implanted with an exemplary extracardiac implantable medical device system.

[0021] Figure 6 is a conceptual diagram showing a front view of a patient implanted with an exemplary extracardiac implantable medical device system showing vertical leads.

[0022] Figure 7 is a conceptual diagram showing a front view of a patient implanted with an exemplary extracardiac implantable medical device system showing vertical and / or horizontal leads.

[0023] Figure 8 is a conceptual diagram showing a front view of a patient implanted with an exemplary extracardiac implantable medical device system including multiple leadless pacing devices.

[0024] Figure 9 is a conceptual diagram showing a front view of a patient implanted with an exemplary extracardiac implantable medical device system and one or more leadless pacing devices.

[0025] Figure 10 is a flowchart of an exemplary technique for delivering therapy via an exemplary extracardiac implantable medical device system.

[0026] Figure 11 is a flowchart of an exemplary technique for implanting one or more leads in a patient.

[0027] Throughout the specification and the drawings, like reference characters represent like elements. DETAILED DESCRIPTION

[0028] According to the techniques of the present disclosure, a system is configured to provide cardiac resynchronization therapy (CRT) by delivering pacing from epicardial electrodes to multiple regions of the heart. For example, the system may include epicardial leads configured to deliver cardiac pacing to the right atrium (RA), right ventricle (RV), and left ventricle (LV).

[0029] Figure 1 is a front view of a patient 12 with an implantable medical device (IMD) system 8 implanted within the thoracic cavity. Referring to the drawings in which like reference indicators refer to like elements, Figures 1 to 3 illustrates a conceptual diagram showing various views of an exemplary epicardial IMD system 8. The IMD system 8 includes an IMD 9 connected to a first lead 10a and a second lead 10b (collectively referred to as "implantable leads 10" or "one or more leads 10"). One or more leads 10 may be implantable medical leads. Figure 1 is a front view of a patient with an epicardial IMD system 8 implanted. Figure 2 is a side view of a patient with an epicardial IMD system 8 implanted. Figure 3 is a transverse view of a patient with an epicardial IMD system 8 implanted.

[0030] The IMD 9 may include a housing that forms an airtight seal around the components of the IMD 9. The housing of the IMD 9 may be formed of a conductive material such as titanium or a titanium alloy, and the housing may serve as a housing electrode (sometimes referred to as a can electrode). In some embodiments, the IMD 9 may be formed to have or may include multiple electrodes on the housing. The IMD 9 may also include a connector assembly (also referred to as a connector block or plug) that includes electrical feedthroughs through which electrical connections are made between the conductors of one or more leads 10 and the electronic components included within the housing of the IMD 9. As will be described in further detail herein, the housing may house one or more processors, memories, transmitters, receivers, sensors, sensing circuits, therapy circuits, power supplies, and other suitable components. The housing may be configured to be implanted within a patient (such as patient 12). Alternatively, the housing may be external to the patient and connected to the proximal end of a lead that extends outside the patient through an incision, for example.

[0031] The IMD 9 is implanted outside the thoracic cavity on the left side of the patient, for example, subcutaneously and outside the rib cage (subcutaneously or submuscularly). In some cases, the IMD 9 may be implanted between the patient's left posterior axillary line and left anterior axillary line. However, the IMD 9 may be implanted at other extra-thoracic locations of the patient, implanted at an intra-thoracic location, or not implanted at all in the case of an external pacemaker.

[0032] An IMD (such as IMD 9) is coupled to one or more leads 10. Leads 10a and 10b may be configured to be placed at multiple epicardial locations, including extravascular locations (i.e., outside of a vessel and / or vasculature) and / or locations within epicardial blood vessels within the thoracic cavity. Lead 10a may include an elongate lead body 13a having a distal portion 16a, and lead 10b may include an elongate lead body 13b having a distal portion 16b. The size of one or more leads 10 may be set to be implanted in an extravascular location near the heart, e.g., within the thoracic cavity as shown in Figures 1 to 3 or outside the thoracic cavity. For example, one or more leads 10 may extend from the IMD 9 toward the center of the patient's torso, e.g., toward the xiphoid process 23 of the patient, subcutaneously and outside the thoracic cage (e.g., subcutaneously, submuscularly, and / or on the diaphragm) to outside the thoracic cavity. At a location near the xiphoid process 23, the lead body 13a and / or the lead body 13b may be bent or otherwise turned upward and extended. The bend may be preformed and / or the lead body 13a or the lead body 13b may be flexible to facilitate the bend.

[0033] In Figures 1 to 3 the example shown, the lead body 13a extends upward within the thoracic cavity in front of the heart 26 and below the sternum 22 in a direction substantially parallel to the sternum 22. In this way, the distal portion 16a of the lead 10a may reside in an extravascular intrathoracic sub-sternal location such that the distal portion 16a of the lead 10a extends upward along the posterior side of the sternum 22 within the anterior portion of the mediastinum 36. The lead body 13b extends upward within the thoracic cavity behind the heart 26 and in front of the spine 35. In this way, the distal portion 16b of the lead 10b may reside in the posterior extravascular intrathoracic portion of the mediastinum 37. The leads 10a and 10b may share a common entry point into the mediastinum. Alternatively, the leads 10a and 10b may have separate entry points in respective portions of the mediastinum. In some examples, the lead 10b may be the only lead implanted in the patient, and the lead 10b may be positioned in the posterior mediastinum 37 (such as to effect posterior mediastinal pacing, sensing, or defibrillation when the current mediastinum is avoided and / or inaccessible for electrode implantation).

[0034] The anterior mediastinum 36 can be considered to be bounded laterally by the pleura 39, posteriorly by the pericardium 38, and anteriorly by the sternum 22. In some cases, the anterior wall of the anterior mediastinum 36 can also be formed by the transversus thoracis muscle and one or more costal cartilages. The anterior mediastinum 36 includes a certain amount of loose connective tissue (such as areolar tissue), adipose tissue, some lymphatic vessels, lymph glands, sub-sternal muscle tissue (e.g., transversus thoracis muscle), the thymus, branches of the intra-thoracic arteries, and the intra-thoracic veins (ITV). The posterior mediastinum 37 can be considered to be bounded laterally by the pleura 39, posteriorly by the vertebral column 35, and anteriorly by the pericardium 38. The posterior mediastinum 37 includes a portion of the descending aorta, the azygos vein and the two hemiazygos veins, the vagus nerve and the splanchnic nerves, the esophagus, the thoracic duct, and some lymph nodes. The mediastinum can be bounded inferiorly by the diaphragm.

[0035] The lead body 13a can extend upward outside of the thoracic cavity (rather than inside the thoracic cavity), for example, subcutaneously or submuscularly above the thorax / sternum. In an extra-thoracic or intra-thoracic example, the lead 10a can be implanted at other locations, such as above or below the sternum, offset to the right or left of the sternum, angled laterally from the proximal or distal end of the sternum, etc. In some examples, the lead 10a can be implanted in an extra-vascular intercostal position (i.e., between the ribs). In some examples, the lead 10a can be implanted within an extra-cardiac blood vessel within the thoracic cavity, such as the ITV, an intercostal vein, or the superior epigastric vein. In some examples, the orientation of the distal portion 16a of the lead 10a can be different from Figures 1 to 3 the illustrated orientation, such as orthogonal to or otherwise transverse to the sternum 22 and / or below the heart 26. In such examples, the distal portion 16a of the lead 10a can be at least partially within the anterior mediastinum 36. The lead 10b can be implanted at other locations. In some examples, one or more leads 10 can be implanted within an extra-cardiac blood vessel within the thoracic cavity, such as the azygos vein, the hemiazygos vein, and the accessory hemiazygos vein. In some examples, the lead 10b can be implanted in an extra-vascular intercostal position (i.e., between the ribs).

[0036] The lead body 13a and the lead body 13b can have a generally tubular or cylindrical shape and can define a diameter of approximately 3 French (Fr) to 9 Fr. However, lead bodies less than 3 Fr and greater than 9 Fr can also be utilized. In another configuration, the lead body 13a and the lead body 13b can have a flat, ribbon-like, or paddle-like shape along at least a portion of the length of the lead body 13a and the lead body 13b, with a solid woven filament or wire mesh structure. In such an example, the width spanning the lead body 13a and the lead body 13b can be between 1 mm and 3.5 mm. Other lead body designs can be used without departing from the scope of the present application.

[0037] The lead bodies 13a and 13b may be formed of a non-conductive material including silicone, polyurethane, fluoropolymer, mixtures thereof, and other suitable materials and shaped to form one or more lumens (not shown), however, these techniques are not limited to such configurations. The distal portions 16a and 16b may be manufactured to be biased in a desired configuration or, alternatively, may be manipulated by a user into a desired configuration. For example, the distal portions 16a and 16b may be constructed of a malleable material such that a user may manipulate the distal portions into a desired configuration that remains unchanged until manipulated into a different configuration.

[0038] The lead body 13a may include a proximal end 14a having a connector 34a configured to couple to the IMD 9 and a distal portion 16a including an electrode configured to deliver electrical energy to or sense electrical signals of the heart. Similarly, the lead body 13b may include a proximal end 14b having a connector 34b configured to couple to the IMD 9 and a distal portion 16b including an electrode configured to deliver electrical energy to or sense electrical signals of the heart. The connectors of the lead bodies 13a and 13b may be industry standard connectors (e.g., IS1, DF1, IS4, DF4, etc.) or proprietary connectors. In some instances, the distal portions 16a and 16b may be anchored to a desired location within the patient's body, such as sub-sternally or subcutaneously, by, for example, suturing the distal portions 16a and 16b to the patient's muscle tissue, tissue, or bone at the xiphoid entry site. In some examples, the distal portions 16a and 16b may be anchored to the patient or by using rigid teeth, tips, barbs, clips, screws, and / or other projecting elements or flanges, discs, compliant teeth, flaps, porous structures such as mesh elements, and metal or non-metal scaffolds, bioadhesive surfaces, and / or any other non-piercing elements that promote tissue growth for engagement.

[0039] The distal portions 16a and 16b may include one or more defibrillation electrodes configured to deliver anti-tachycardia, such as cardioversion / defibrillation, shocks to the heart 26 of the patient 12. In some examples, one or more of the distal portions 16a and 16b include a plurality of defibrillation electrodes spaced apart from each other along the length of the distal portion 16. In Figures 1 to 3In the example shown, the distal portion 16a of lead 10a includes two defibrillation electrodes 28a and 28b, and the distal portion 16b of lead 10b includes one defibrillation electrode 28c (collectively referred to as "defibrillation electrodes 28"). In other examples, each distal portion 16 may include one defibrillation electrode 28, each distal portion 16 may include more than one defibrillation electrode 28, or one of the distal portions 16 (such as distal portion 16b) may not include a defibrillation electrode 28. In some examples, the defibrillation electrodes 28 may be electrically isolated electrodes, or electrically common segments of a single defibrillation electrode.

[0040] The defibrillation electrodes 28 may be disposed around or within the lead bodies 13a and 13b of the distal portions 16a and 16b, or alternatively, may be embedded within the walls of the lead bodies 13a and 13b. In one configuration, the defibrillation electrodes 28 may be coil electrodes formed of a conductor. The conductor may be formed of one or more conductive polymers, ceramics, metal-polymer composites, semiconductors, metals, or metal alloys, including but not limited to one of platinum, tantalum, titanium, niobium, zirconium, ruthenium, indium, gold, palladium, iron, zinc, silver, nickel, aluminum, molybdenum, stainless steel, MP35N, carbon, copper, polyaniline, polypyrrole, and combinations of other polymers. In another configuration, each of the defibrillation electrodes 28 may be a flat strip electrode, paddle electrode, braided or woven electrode, mesh electrode, directional electrode, patch electrode, or another type of electrode configured to deliver cardioversion / defibrillation shocks to the heart 26 of the patient 12.

[0041] The defibrillation electrodes 28 may be electrically connected to one or more conductors, which may be disposed within a lumen defined by the body walls of the lead bodies 13a and 13b or within one or more insulated lumens (not shown) defined by the lead bodies 13a and 13b. In an exemplary configuration, each of the defibrillation electrodes 28 is connected to a common conductor such that a voltage may be applied simultaneously to all of the defibrillation electrodes 28 to deliver an antitachycardia shock to the heart 26. In other configurations, the defibrillation electrodes 28 may be attached to separate conductors such that each defibrillation electrode 28 may apply a voltage independently of the other defibrillation electrodes 28. In such a case, the IMD 9 or one or more of the leads 10 may include one or more switches or other mechanisms to electrically connect the defibrillation electrodes together to act as a common polarity electrode such that, in addition to being able to apply voltages independently, a voltage may also be applied simultaneously to all of the defibrillation electrodes 28.

[0042] One or more leads 10 may include a plurality of electrodes, wherein the one or more leads 10 are configured to position the plurality of electrodes at a plurality of epicardial locations to deliver cardiac pacing to the right atrium (RA), right ventricle (RV), and left ventricle (LV) of the heart 26 of a patient 12. In some examples, cardiac pacing may include cardiac resynchronization therapy (CRT). The distal portions 16a and 16b may include one or more pacing and / or sensing electrodes configured to deliver pacing pulses to the heart 26 and / or sense electrical activity of the heart 26. Such electrodes may be referred to as pacing electrodes, sensing electrodes, or pacing / sensing electrodes. In Figures 1 to 3 the example shown, the distal portion 16a includes two pacing / sensing electrodes 32a and 32b, and the distal portion 16b includes one pacing / sensing electrode 32c (collectively referred to as "pacing / sensing electrodes 32" or "the plurality of electrodes 32"). However, in some examples, the one or more leads 10 may be configured to position the pacing / sensing electrodes 32 to deliver cardiac pacing to the LA, LV, and RV and / or monitor the LA, LV, and RV to effect CRT.

[0043] In Figures 1 to 3 the example shown, a subset of the plurality of electrodes 32 may be configured to pace certain regions of the heart 26, where the subset may include one or more electrodes. For example, a first electrode subset that may include one or more electrodes may be configured to pace the RA and RV, and a second electrode subset that may include one or more electrodes may be configured to pace the LV. The one or more leads 10 may be configured to position a subset of the plurality of electrodes 32 to pace certain regions of the heart 26. For example, a first lead (such as lead 10a) may be configured to position a first subset of the plurality of electrodes 32 (such as electrodes 32a and 32b) to deliver pacing to the RA and RV. In some examples, a second lead (such as lead 10b) may be configured to position a second subset of the plurality of electrodes 32 (such as electrode 32c) to deliver pacing to the LV. In other examples, a first lead (such as lead 10a) may be configured to position a first electrode subset of the plurality of electrodes to deliver pacing to the RA, and a second lead (such as lead 10b) may be configured to position a second subset of the plurality of electrodes to deliver pacing to the LA and LV. In other examples, a first lead (such as lead 10a) may be configured to position a first electrode subset of the plurality of electrodes to deliver pacing to the RA and RV, and a second lead (such as lead 10b) may be configured to position a second subset of the plurality of electrodes to deliver pacing to the LA and LV. In the case where a single electrode senses the RA and LA respectively, independent timing sequences may be coordinated for the RV and LV.

[0044] In Figures 1 to 3In the illustrated example, the pacing / sensing electrode 32b is positioned between the defibrillation electrodes 28a and 28b of the lead 10a, e.g., within the gap between the defibrillation electrodes, and the pacing / sensing electrode 32a is positioned more proximally along the distal portion 16a than the proximal defibrillation electrode 28a. In some examples, more than one of the plurality of electrodes 32 may be present within the gap between the defibrillation electrodes 28. In some examples, the electrodes are additionally or alternatively located distally of the most distal defibrillation electrode 28b. Alternatively, the pacing / sensing electrode 32c may be positioned distally or proximally compared to the defibrillation electrode 28c on the lead 10b (although in the example of Figure 1 , the pacing / sensing electrode 32c is positioned proximally compared to the defibrillation electrode 28c on the lead 10). Alternatively, the lead 10b may include a plurality of pacing / sensing electrodes 28c and one or more defibrillation electrodes 28b. Figure 1 In the example of , the pacing / sensing electrode 32c is positioned proximally compared to the defibrillation electrode 28c on the lead 10. Alternatively, the lead 10b may include a plurality of pacing / sensing electrodes 28c and one or more defibrillation electrodes 28b.

[0045] Within the IMD system 8, the IMD 9 may be configured to deliver cardiac pacing via the plurality of electrodes 32. The plurality of electrodes 32 may be configured to deliver cardiac pacing. The IMD 9 may be configured to deliver antitachycardia shocks via one or more electrodes configured to deliver antitachycardia shocks. One or more leads 10 include one or more electrodes configured to deliver antitachycardia shocks. The plurality of electrodes 32 may be configured to deliver low voltage electrical pulses to the heart or may sense cardiac electrical activity, e.g., depolarization and repolarization of the heart. Thus, the plurality of electrodes 32 may be referred to herein as pacing / sensing electrodes 32. In one configuration, the plurality of electrodes 32 are annular electrodes. However, in other configurations, the plurality of electrodes 32 may be any of a variety of different types of electrodes, including annular electrodes, short coil electrodes, paddle electrodes, hemispherical electrodes, or directional electrodes. Each of the plurality of electrodes 32 may be the same or a different type of electrode than the other electrodes of the plurality of electrodes 32. The plurality of electrodes 32 may be electrically isolated from adjacent defibrillation electrodes 28 by including an electrically insulating layer of material between the plurality of electrodes 32 and the adjacent defibrillation electrodes 28. Each of the plurality of electrodes 32 may have its own separate conductor such that a voltage may be applied to or sensed via each electrode independently of another electrode of the plurality of electrodes 32.

[0046] The electrode 28 is referred to as a defibrillation electrode, and the plurality of electrodes 32 are referred to as pacing / sensing electrodes because they may have different physical structures to achieve different functions. The defibrillation electrode 28 may be larger than the pacing / sensing electrodes 32, for example, having a larger surface area, and may thus be configured to deliver antitachycardia shocks having a relatively higher voltage than pacing pulses. The relatively smaller-sized pacing / sensing electrodes 32 may provide advantages over the defibrillation electrode for delivering pacing pulses and sensing intrinsic cardiac activity, such as a lower pacing capture threshold and / or better sensing signal quality. However, the defibrillation electrode 28, such as in combination with the pacing / sensing electrodes 32, may be used to deliver pacing pulses and / or sense the electrical activity of the heart. In some examples, one or more leads 10 may include only the pacing / sensing electrodes 32 and not the defibrillation electrode 28 to implement CRT, also referred to as "CRT-P".

[0047] The proximal end 14a of the lead body 13a may include a connector 34a to electrically couple the lead 10a to the IMD 9. The proximal end 14b of the lead body 13b may include a connector 34b to electrically couple the lead 10b to the IMD 9. The IMD 9 may also include a connector assembly that includes electrical feedthroughs through which electrical connections are made between one or more contacts on the connectors 34 of one or more leads 10 and electronic components included within the housing. The housing of the IMD 9 may house one or more processors, memories, transmitters, receivers, sensors, sensing circuits, therapy circuits, power sources (capacitors and batteries), and / or other components. The components of the IMD 9 may generate and deliver electrical therapies such as antitachycardia pacing, cardioversion, or defibrillation shocks, post-shock pacing, bradycardia pacing, and / or CRT.

[0048] In some examples, the undulating configuration of the distal portion 16a of lead 10a and including electrodes 32a and 32b between defibrillation electrodes 28a and 28b can provide multiple treatment vectors for delivering electrotherapy to the heart. For example, at least a portion of defibrillation electrodes 28a and 28b and one of pacing / sensing electrodes 32a and 32b can be disposed over the right ventricle, right atrium, or any chamber of the heart such that pacing pulses and antitachycardia shocks can be delivered to the heart. The housing of IMD 9 can be charged with or used as a different polarity than the polarity of one or more of defibrillation electrodes 28a and 28b and / or electrodes 32a and 32b such that electrical energy can be provided to the heart between the housing and defibrillation electrodes 28a and 28b and / or electrodes 32a and 32b. In some examples, defibrillation electrode 28c and pacing / sensing electrode 32c can be disposed on the left ventricle such that pacing pulses and / or antitachycardia shocks can be delivered to the heart. In some examples, a defibrillation vector can be formed across the heart between defibrillation electrode 28c and at least one of defibrillation electrodes 28a or 28b. In some examples, lead 10a including electrodes 32a, electrode 32b, defibrillation electrode 28a, and defibrillation electrode 28b and lead 10b including defibrillation electrode 28c and pacing / sensing electrode 32c can provide multiple treatment vectors, including a transcardiac impedance vector. In some examples, lead 10a can include only pacing / sensing electrode 32a and / or 32b. In some examples, lead 10a can include only defibrillation electrode 28a and / or 28b. In some examples, lead 10b can include only pacing / sensing electrode 32c. In some examples, lead 10b can include only defibrillation electrode 28c.

[0049] When a voltage is applied to each defibrillation electrode, each defibrillation electrode in defibrillation electrodes 28 can have the same polarity as each other defibrillation electrode such that shocks can be delivered from all defibrillation shocks together. In a first example, defibrillation electrodes 28a and 28b are electrically connected to a common conductor within lead body 13a and can have the same polarity. However, in other examples, defibrillation electrodes 28a and 28b can be coupled to separate conductors located within lead body 13a and can thus each have a different polarity such that electrical energy can flow between defibrillation electrodes 28a and 28b, or between one of defibrillation electrodes 28a and 28b and one of pacing / sensing electrodes 32a or 32b or a housing electrode to provide antitachycardia shocks, pacing therapy, and / or sensing of cardiac depolarization. In such a case, defibrillation electrodes 28a and 28b can still be electrically coupled together, for example, via one or more switches within IMD 9, to have the same polarity.

[0050] In some examples, the distal portion 16a of lead 10a and / or the distal portion 16b of lead 10b may include one or more shields. The one or more shields may be configured to block an electric field from being delivered electrotherapeutically via the electrodes (e.g., from a pacing pulse) in a direction away from the heart from the electrodes (e.g., in a forward or backward direction). In this way, the shield may reduce the likelihood that the electric field will stimulate extracardiac tissue, such as sensory or motor nerves. Additionally, the shield may direct the electric field toward the heart, allowing a lower energy level of pacing pulse to capture the heart compared to what may be required without the shield. The lower energy pacing pulse may also reduce the likelihood of stimulating extracardiac tissue with the pacing pulse delivered via the pacing electrodes, and may result in less power consumption by the IMD 9 and thus extend the useful life of the IMD 9. The techniques of the present disclosure may be applied to implantable systems other than the IMD 9, including but not limited to bradycardia pacemaker systems. By way of example, a lead that does not include defibrillation electrodes may include one or more shields and may be used with a pacemaker system that does not have defibrillation capabilities.

[0051] According to the techniques of the present disclosure, the pacing electrode of the pacing / sensing electrode 32 may be configured to reduce the pacing voltage threshold. For example, a conductive surface may be disposed on the shield and electrically coupled to the pacing electrode, which may reduce the resistance of the pacing electrode and / or expand the electric field generated by the pacing electrode. Reducing the resistance of the pacing electrode and / or expanding the electric field generated by the pacing electrode may reduce the amount of electrical current used to generate a pacing pulse, which may reduce the amount of power used by the IMD 9.

[0052] Figure 4 is a functional block diagram of an exemplary configuration of the electronic and other components of the IMD 9. The IMD 9 includes a processing circuit 402, a sensing circuit 404, a therapy delivery circuit 406, a sensor 408, a communication circuit 410, and a memory 412. In some examples, the IMD 9 may include more or fewer components. The described circuits and other components may be implemented together on shared hardware components or separately as discrete but interoperable hardware or software components. The depiction of the different features is intended to highlight different functional aspects and does not necessarily imply that such circuits and other components must be implemented by separate hardware or software components. Instead, the functions associated with one or more circuits and components may be performed by separate hardware or software components or integrated within shared or separate hardware or software components.

[0053] The sensing circuit 404 may be electrically coupled to some or all of the electrodes 416, which may correspond to any of the defibrillation electrodes, pacing / sensing electrodes, and can electrodes described herein. The sensing circuit 404 is configured to obtain signals sensed via one or more combinations of the electrodes 416 and process the signals obtained.

[0054] The components of the sensing circuit 404 can be analog components, digital components, or a combination thereof. The sensing circuit 404 can include, for example, one or more sense amplifiers, filters, rectifiers, threshold detectors, analog-to-digital converters (ADCs), etc. The sensing circuit 404 can convert the sensed signal into digital form and provide the digital signal to the processing circuit 402 for processing or analysis. For example, the sensing circuit 404 can amplify the signal from the sensing electrode and convert the amplified signal into a multi-bit digital signal via an ADC. The sensing circuit 404 can also compare the processed signal with a threshold to detect the presence of atrial or ventricular depolarization (e.g., P wave or R wave) and indicate the presence of atrial depolarization (e.g., P wave) or ventricular depolarization (e.g., R wave) to the processing circuit 402. As Figure 4 shown, the IMD 9 can additionally include one or more sensors 408, such as one or more accelerometers, which can be configured to provide signals indicating other parameters of the patient, such as activity or posture, to the processing circuit 402.

[0055] The processing circuit 402 can process the signals from the sensing circuit 404 to monitor the electrical activity of the heart 26 of the patient 12. The processing circuit 402 can store the signals obtained by the sensing circuit 404 and any generated EGM waveforms, marker channel data, or other data derived from the sensed signals in the memory 412. The processing circuit 402 can analyze the EGM waveforms and / or marker channel data to detect arrhythmias (e.g., bradycardia or tachycardia). In response to detecting a cardiac event, the processing circuit 402 can control the therapy delivery circuit 406 to deliver a desired therapy to treat the cardiac event, such as a defibrillation shock, cardioversion shock, ATP, post-shock pacing, bradycardia pacing, or CRT.

[0056] The therapy delivery circuit 406 is configured to generate an electrical therapy and deliver the electrical therapy to the heart 26. The therapy delivery circuit 406 can include one or more pulse generators, capacitors, and / or other components capable of generating and / or storing energy to deliver pacing therapy, defibrillation therapy, cardioversion therapy, CRT, other therapies, or a combination of therapies. The therapy delivery circuit 406 can be configured to generate and deliver pacing pulses having an amplitude and timing specified by the processing circuit 402. For the delivery of CRT, for example, the processing circuit 402 can control the therapy delivery circuit to deliver pacing pulses according to one or more atrioventricular (AV) intervals from intrinsic or paced atrial events and / or one or more ventriculo-ventricular (VV) intervals from intrinsic or paced ventricular events. The values of such intervals can be user-programmed and / or variable based on physiological parameters sensed, for example, via the sensor 408.

[0057] In some cases, the therapy delivery circuit 406 may include a first set of components configured to provide pacing therapy and a second set of components configured to provide defibrillation therapy. In some cases, the therapy delivery circuit 406 may utilize the same set of components to provide both pacing therapy and defibrillation therapy. In yet other cases, the therapy delivery circuit 406 may share some of the defibrillation therapy components and pacing therapy components while using other components solely for defibrillation or pacing. The processing circuit 402 may control the therapy delivery circuit 406 to deliver the generated therapy to the heart 26 via one or more combinations of the electrodes 416. Although Figure 4 not shown, the IMD 9 may include a switching circuit configurable by the processing circuit 402 to control which of the electrodes 416 are connected to the therapy delivery circuit 406 and the sensing circuit 404.

[0058] The communication circuit 410 may include any suitable hardware, firmware, software, or any combination thereof for communicating with another device, such as a clinician programmer, a patient monitoring device, etc. For example, the communication circuit 410 may include appropriate modulation components, demodulation components, frequency conversion components, filtering components, and amplifier components for transmitting and receiving data via an antenna.

[0059] The various components of the IMD 9 may include any one or more processors, controllers, digital signal processors (DSPs), application specific integrated circuits (ASICs), field programmable gate arrays (FPGAs), or equivalent discrete or integrated circuits, including analog circuits, digital circuits, or logic circuits. The processing circuit 402 may include fixed function circuitry and / or programmable processing circuitry. The functions ascribed to the processing circuit 402 herein may be embodied as software, firmware, hardware, or any combination thereof.

[0060] The memory 412 may include computer-readable instructions that, when executed by the processing circuit 402 or other components of the IMD 9, cause one or more components of the IMD 9 to perform the various functions ascribed to those components in the present disclosure. The memory 412 may include any volatile medium, non-volatile medium, magnetic medium, optical medium, or electrical medium, such as random access memory (RAM), read only memory (ROM), non-volatile RAM (NVRAM), static non-volatile RAM (SRAM), electrically erasable programmable ROM (EEPROM), flash memory, or any other non-volatile computer-readable storage medium.

[0061] The leads and systems described herein can be used, at least in part, within the sub-sternal space, e.g., within the anterior and posterior mediastinum of a patient, to provide an extra-cardiac IMD system. An implanter (e.g., a physician) can implant the distal portion of a lead within the thoracic cavity using any of a plurality of implant tools (e.g., a tunneling rod, a sheath, or other tools that can traverse a septal attachment and form a tunnel at a sub-sternal location). For example, the implanter can create an incision near the center of the patient's torso, e.g., and introduce the implant tool through the incision into the sub-sternal location. The implant tool is advanced upward from the incision along the posterior side of the sternum located at the sub-sternal location. The distal portion of the lead is introduced into the tunnel via the implant tool (e.g., via the sheath). When the distal portion is advanced through the sub-sternal tunnel, the distal portion is relatively straight. A pre-formed or shaped undulating configuration is flexible enough to be straightened when guiding the lead through the sheath of the implant tool or other lumen or passageway. Once the distal portion is in place, the implant tool is withdrawn toward the incision and removed from the patient's body while leaving the lead in place along the sub-sternal path. When the implant tool is withdrawn, the distal end of the lead assumes its pre-formed undulating configuration and the shield transitions to its deployed configuration.

[0062] In some examples, the distal portion of the lead can be oriented orthogonally or otherwise laterally to the sternum and / or below the heart, rather than extending upward along the sternum. In such examples, according to any of the examples described herein, the lead can include one or more shields that cover a portion of the outer surface of one or more electrodes, e.g., forward and / or downward portions and / or in a direction associated with an anatomical feature such as the septum. Such shields can block an electric field in a direction away from the heart, which can be a forward, downward, backward, and / or upward direction. In some examples, the distal portion of the lead can be placed between the heart and the lungs and within the pleural cavity.

[0063] According to the techniques of the present disclosure, the pacing electrode of electrode 416 can be configured to reduce the pacing voltage threshold. For example, a conductive surface can be provided on the shield and electrically coupled to the pacing electrode, which can reduce the resistance of the pacing electrode and / or expand the electric field generated by the pacing electrode. Reducing the resistance of the pacing electrode and / or expanding the electric field generated by the pacing electrode can reduce the amount of electrical current used to generate a pacing pulse, which can reduce the amount of power used by the IMD 9.

[0064] As Figures 5 to 9 shown, placement of the lead and / or leadless pacing device within various extra-cardiac locations can achieve the same as described above with respect to Figures 1 to 3The described placement provides the same or substantially similar effects. Alternatively, the location may include, but is not limited to, the pleural sac or pleural cavity, the pericardium or epicardial region, or some intrathoracic, non-cardiac / epicardial vascular location. Combinations of various pacing devices are also illustrated, including devices with leads and leadless pacing devices, which may be used alone or in combination with each other. Device placement variations may include not only the location of the device, but also the orientation of the device (e.g., horizontal, vertical, etc.).

[0065] Figure 5 is a conceptual diagram illustrating a front view of a patient 112 implanted with an exemplary epicardial implantable medical device system 108. The system 108 includes an IMD 109 connected to a first lead 110a and a second lead 110b. As Figure 5 shown in the example of, the distal portions 116a of lead 110a and the distal portion 116b of lead 110b may be placed in the pleural cavity between the heart 126 and the lungs 127 (e.g., intrapleural placement). Leads 110a and 110b (in their entirety) may be configured as described above with respect to Figures 1 to 3 one or more leads 10, except as described herein. Leads 110a and 110b may be configured to be placed in the pleural cavity (e.g., intrapleural placement). In some examples, in the case where lead 110a is configured to position a first subset of a plurality of electrodes (such as electrodes 132a and 132b) to pace the RA and RV, lead 110a may be positioned in the right pleural cavity 151a or the left pleural cavity 151b (collectively referred to as "pleural cavity 151"). Lead 110a may be positioned anteriorly with respect to the heart 126. Lead 110a may be positioned laterally with respect to the heart 126. Lead 110a may be positioned anterolaterally with respect to the heart 126. In some examples, in the case where lead 110b is configured to position a second subset of a plurality of electrodes (such as electrode 132c) to pace the LV, lead 110b may be positioned in the right pleural cavity 151a or the left pleural cavity 151b. Lead 110b may be positioned posteriorly with respect to the heart 126. Lead 110b may be positioned laterally with respect to the heart 126. Lead 110b may be positioned posterolaterally with respect to the heart 126. In some examples, the first subset of the plurality of electrodes 132 or the second subset of the plurality of electrodes 132 may include one or more electrodes. As Figure 5As shown in the example of FIG. 0, lead 110a may be placed in the right pleural cavity 151a in front of the heart 126, and lead 110b may be placed in the left pleural cavity 151b behind the heart 126. However, alternative arrangements of lead 110 are conceivable. Lead 110a may be placed in the left pleural cavity 151b in front of the heart 126, and lead 110b may be placed in the right pleural cavity 151a behind the heart 126. Lead 110a and lead 110b may both be placed in the right pleural cavity 151a (one behind the heart 126 and one in front of the heart), or lead 110a and lead 110b may both be placed in the left pleural cavity 151b (one behind the heart 126 and one in front of the heart). Lead 110a and lead 110b may share a common entry point into the pleural cavity 151. For example, a single incision site near the xiphoid process may facilitate delivery of one or more leads 110 into the pleural cavity. Lead 110a and lead 110b may have different entry points into the pleural cavity 151. For example, two or more incisions near the xiphoid process may facilitate delivery of one or more leads 110, such as where lead 110a is placed into the pleural cavity through a first incision and lead 110b is placed into the pleural cavity through a second incision. For an intercostal approach, a single incision may be made to facilitate delivery of one or more leads 110, or two or more incisions may be made to facilitate delivery of one or more leads 110.

[0066] In some examples, placement of one or more leads 110 may occur in a combination of positions within the mediastinum or pleural cavity. For example, lead 110a may be placed in the mediastinum while lead 110b is placed in the pleural cavity. As another example, lead 110a may be placed in the pleural cavity while lead 110b is placed in the mediastinum. In some examples, in the case where lead 110a is placed in the mediastinum and lead 110b is placed in the pleural cavity, lead 110a may be placed in front of the heart 126 in the mediastinum and lead 110b may be placed behind the heart 126 in the pleural cavity. In some examples, in the case where lead 110a is placed in the pleural cavity and lead 110b is placed in the mediastinum, lead 110a may be placed in front of the heart 126 in the pleural cavity and lead 110b may be placed behind the heart 126 in the mediastinum.

[0067] Figure 6 is a conceptual diagram showing a front view of a patient 212 implanted with an exemplary extracorporeal implantable medical device system 208 including leads configured to be vertically oriented within the patient 212. Figure 7 is a conceptual diagram showing a front view of a patient 312 implanted with an exemplary extracorporeal implantable medical device system 308 including leads configured to be vertically and / or horizontally oriented within the patient 312. As Figures 6 to 7As shown in the example of, various orientations of one or more leads can be envisioned, whether the one or more leads are placed in the mediastinum or in the pleural cavity. The various orientations of the leads can allow for a variety of different treatment carriers. System 208 includes an IMD 209 connected to a first lead 210a and a second lead 210b. Leads 210a and 210b (complete) can be configured as described above for one or more leads 10 of Figures 1 to 3 except as described herein. In Figure 6 the example of, one or more leads 210 can be substantially vertical. Additionally, one or more leads 210 can be substantially parallel. For example, the distal portion 216a of lead 210a and the distal portion 216b of lead 210b can be perpendicular to the mediastinum or within the pleural cavity. In this way, a first lead (such as the distal portion 216a of lead 210a) and a second lead (such as the distal portion 216b of lead 210b) can be substantially parallel. However, one or more leads 210 can also be substantially horizontal.

[0068] In Figure 7 the example of, one or more leads 310 can be horizontal or substantially horizontal. System 308 includes an IMD 309 connected to a first lead 310a and a second lead 310b. Leads 310a and 310b (complete) can be configured as described above for one or more leads 10 of Figures 1 to 3 except as described herein. In some examples, the distal portion 316b of lead 310b can be horizontal within the mediastinum or within the pleural cavity. In this example, the distal portion 316a of lead 310a can be vertical. In this way, a first lead (such as the distal portion 316a of lead 310a) and a second lead (such as the distal portion 316b of lead 310b) can be substantially perpendicular. Other orientations and combinations of orientations of one or more leads 310 are also possible. For example, the distal portion 316a of lead 310a can be horizontal while the distal portion 316b of lead 310b can be vertical. Additionally, both the distal portion 316a of lead 310a and the distal portion 316b of lead 310b can be horizontal. In addition to horizontal and vertical orientations, the distal portion 316a of lead 310a and the distal portion 316b of lead 310b can be diagonal within patient 312. The distal portion 316a of lead 310a and the distal portion 316b of lead 310b can be neither parallel nor perpendicular (e.g., set at an angle or skewed).

[0069] In some examples, one or more leads 310 may be placed horizontally or substantially horizontally in one or more on-diaphragm positions. In such examples, one or more leads 310 may be placed over the diaphragm of a patient 312. In such examples, one or more on-diaphragm positions may be within the mediastinum of the patient 312. In such examples, one or more pacing / sensing electrodes on one or more leads 310 may point upward toward the heart. In such examples, the electrodes pointing upward toward the heart may be paddle electrodes. In such examples, one or more shields on one or more leads 310 may point toward the diaphragm.

[0070] Figure 8 FIG. 4 is a conceptual diagram showing a front view of a patient 512 implanted with an exemplary extracorporeal implantable medical device system including a plurality of leadless pacing devices. Figure 9 FIG. 6 is a conceptual diagram showing a front view of a patient 612 implanted with an exemplary extracorporeal implantable medical device system and a plurality of leadless pacing devices. As Figures 8 to 9 shown in the example of FIG. 8, a leadless pacing system including one or more leadless pacing devices may be used in combination with or in place of an IMD system. In Figure 8 the example of FIG. 10, the leadless pacing system 508 may include a first leadless pacing device 589a, a second leadless pacing device 589b, and a third leadless pacing device 589c (collectively referred to as "the plurality of leadless pacing devices 589"). The plurality of leadless pacing devices 589 may be configured to be positioned in a plurality of extracorporeal positions (such as extravascularly or within one or more extracorporeal blood vessels). In Figure 8 the example of FIG. 12, the leadless pacing device 589a includes an electrode 582a, the leadless pacing device 589b includes an electrode 582b, and the leadless pacing device 589c includes an electrode 582c (collectively referred to as "the plurality of electrodes 582"). The plurality of leadless pacing devices may be configured to deliver cardiac pacing to the RA, RV, LV, or any combination thereof via the plurality of electrodes 582 on the plurality of leadless pacing devices 589. In some examples, the plurality of leadless pacing devices may additionally or alternatively capture the LA together with or in place of the RA, RV, LV. In some examples, cardiac pacing may include cardiac resynchronization therapy (CRT). The plurality of leadless pacing devices 589 may be configured to communicate with each other or with an IMD system. The plurality of leadless pacing devices 489 may be placed in a subxiphoid position substantially similar to one or more of the leads previously described. For example, one or more of the plurality of leadless pacing devices 589 may be positioned within the mediastinum of the patient 512. One or more of the plurality of leadless pacing devices 589 may be positioned within the pleural cavity of the patient 512.

[0071] In Figure 8In the example, all pacing is delivered via a plurality of leadless pacing devices 589. A first subset of leadless pacing devices, which may include leadless pacing device 589a and leadless pacing device 589b, may be positioned to pace the RA and RV. For example, a first subset of leadless pacing devices, which may include leadless pacing device 589a and leadless pacing device 589b, may be placed in the anterior mediastinum of patient 512. As another example, a first subset of leadless pacing devices, which may include leadless pacing device 589a and leadless pacing device 589b, may be placed in the anterior pleural cavity of patient 512. A second subset of leadless pacing devices, which may include leadless pacing device 589c, may be positioned to pace the LV. For example, a second subset of leadless pacing devices, which may include leadless pacing device 589c, may be placed in the posterior mediastinum of patient 512. As another example, a second subset of leadless pacing devices, which may include leadless pacing device 589c, may be placed in the posterior pleural cavity of patient 512. A first subset of the plurality of leadless pacing devices 589 may be configured to be positioned in the right pleural cavity, and a second subset of the plurality of leadless pacing devices 589 may be configured to be positioned in the left pleural cavity. A first subset of the plurality of leadless pacing devices 589 may be configured to be positioned in the left pleural cavity, and a second subset of the plurality of leadless pacing devices 589 may be configured to be positioned in the right pleural cavity.

[0072] The plurality of leadless pacing devices 589 may be positioned in various orientations, whether the plurality of leadless pacing devices 589 are placed in the mediastinum or in the pleural cavity. One or more of the plurality of leadless pacing devices 589 may be substantially vertical. One or more of the plurality of leadless pacing devices 589 may be substantially horizontal. Some of the plurality of leadless pacing devices 589 may be substantially vertical while other of the plurality of leadless pacing devices 589 may be substantially horizontal. In this way, some of the plurality of leadless pacing devices 589 may be substantially parallel while other of the plurality of leadless pacing devices 589 may be substantially perpendicular.

[0073] As Figure 8As shown in the example of, each leadless pacing device may include electrodes. A plurality of leadless pacing devices 589 may include a plurality of electrodes 582 configured to deliver cardiac pacing. Cardiac pacing delivered by one or more leadless pacing devices may include cardiac resynchronization therapy (CRT). The plurality of leadless pacing devices 589 may be configured to communicate wirelessly with each other or with an IMD system. In some examples, a timing sequence may allow coordination between the plurality of leadless pacing devices 589 to deliver therapy. For example, the timing sequence may include following the RA to coordinate an appropriate delay for delivering therapy to the RV and LV. Additionally or alternatively, the timing sequence may include following the LA to coordinate an appropriate delay for delivering therapy to the RV and LV. Additionally or alternatively, the timing sequence may include following the RA for the RV and following the LA for the LV. The coordinated timing sequence may self-correct periodically. In some examples, the timing sequence may include following the RA for each beat. In some examples, the timing sequence may include following the LA for each beat. In some examples, the timing sequence may include following the RA for each beat and following the LA only periodically. In some examples, the timing sequence may include following the LA for each beat and following the RA only periodically.

[0074] In Figure 9 the example of, the pacing system 608 may include one or more leads 610 (such as lead 610a) and one or more leadless pacing devices 689 (such as leadless pacing device 689c). One or more leadless pacing devices 689 may be used in combination with or in place of the one or more leads 610. Lead 610a may be connected to the IMD 609. Lead 610a may be configured as described above with respect to Figures 1 to 3 one or more leads 10 of, unless described herein. Leadless pacing device 689c may be configured as described above with respect to Figure 8 the plurality of leadless pacing devices 589 of. Any number of leads having a plurality of electrodes may be used in combination with any number of leadless pacing devices to achieve a desired result. In some examples, the distal portion 616a of lead 610a may be implanted substantially parallel to leadless pacing device 689c. In some examples, the distal portion 616a of lead 610a may be implanted substantially perpendicular to leadless pacing device 689c. In some examples, the leadless pacing device may include an extension section such that the leadless pacing device may capture both the atrium and the ventricle.

[0075] As Figure 9As shown in the example of, one or more leads 610 (such as lead 610a) may be configured to position a plurality of electrodes at a plurality of epicardial locations to deliver cardiac pacing to a first subset of the RA, RV, and LV, and one or more leadless pacing devices may be configured to deliver cardiac pacing to a second subset of the RA, RV, and LV. In some examples, the first subset of the RA, RV, and LV may include the RA and RV, and the second subset of the RA, RV, and LV includes the LV. In some examples, the first subset of the RA, RV, and LV may include the LV, and the second subset of the RA, RV, and LV includes the RA and RV.

[0076] Figure 10 is a flowchart of an exemplary technique for delivering therapy via an exemplary epicardial implantable medical device system. Figure 10 The techniques of may be used in combination with any of the devices or systems described in connection with Figures 1 to 9 and are described with respect to Figures 1 to 3 system 8 of and Figure 8 system 508 of. Technique 1000 may include positioning a plurality of electrodes 32 via one or more leads 10 including a plurality of electrodes 32 to deliver cardiac pacing to the RA, RV, and LV (1002). In other examples, one or more leads 10 may include a plurality of electrodes configured to additionally or alternatively capture the LA with or instead of the RA, RV, and LV. As described above, the first lead 10a may be configured to position a first subset of the plurality of electrodes 32 to deliver cardiac pacing to the RA and RV, and the second lead 10b may be configured to position a second subset of the plurality of electrodes 32 to deliver cardiac pacing to the LV. The first lead 10a having the first subset of electrodes may be placed in the anterior mediastinum or the anterior pleural cavity. The second lead 10b having the second subset of electrodes may be placed in the posterior mediastinum or the posterior pleural cavity. The first lead 10a and the second lead 10b may share a common entry point into the mediastinum or a common entry point into the pleural cavity. The first lead 10a may be configured to be positioned in the right pleural cavity, and the second lead 10b may be configured to be positioned in the left pleural cavity. The first lead 10a may be configured to be positioned in the left pleural cavity, and the second lead 10b may be configured to be positioned in the right pleural cavity. The first lead 10a may be positioned perpendicular or parallel to the second lead 10b. In other examples, the technique may include positioning a plurality of electrodes 32 via one or more leads 10 including a plurality of electrodes 32 to deliver cardiac pacing to the LA, LV, and RV.

[0077] Technique 1000 may also include delivering cardiac pacing to the RA, RV, and LV of a patient's heart (1004) via a plurality of electrodes 32 positioned at a plurality of extra-cardiac locations via an IMD coupled to one or more leads. Additionally, the technique may include delivering cardiac pacing to the RA, RV, LV, or any combination thereof via one or more leadless pacing devices 589. As discussed above, the leadless pacing device 589 may be used in combination with an IMD having one or more leads 10 or in place of an IMD having the one or more leads. The leadless pacing device 589 may be configured to be positioned in the mediastinum or pleural cavity of the patient. The leadless pacing device 589 may be configured to be positioned within one or more extra-cardiac blood vessels within the patient. The leadless pacing device 589 may be placed parallel or perpendicular to other leadless pacing devices, or parallel or perpendicular to one or more leads 10 of an IMD as discussed above.

[0078] In some examples, the cardiac pacing delivered to the RA, RV, and LV is CRT. In other examples, the cardiac pacing that may be delivered to the LA, LV, and RV is CRT. In some examples, the plurality of electrodes 32 are configured to deliver cardiac pacing and one or more of the electrodes 32 are configured to deliver antitachycardia shocks. The IMD may include an ICD configured to deliver antitachycardia shocks via one or more electrodes configured to deliver antitachycardia shocks.

[0079] Figure 11 is a flow diagram of an exemplary technique for implanting one or more leads within a patient. Figure 11 The technique of may be used in combination with any of the devices or systems described in connection with Figures 1 to 9 and is described with respect to the system 8 of Figures 1 to 3 The technique may be applied to implanting one or more leads at one or more extra-cardiac locations, including but not limited to the mediastinum and / or pleural cavity of the patient. Technique 1100 may include creating an access point (1102) into the patient 12. The access point may include an incision formed on the skin / tissue of the patient 12 near or below the xiphoid process. Additionally, the access point may include an incision formed, for example, via thoracotomy in an intercostal location (i.e., between the ribs) on the skin / tissue of the patient 12. Additionally, the access point may include an incision near the manubrium. When accessing via an incision near the manubrium, the anterior mediastinum, posterior mediastinum, anterior pleural cavity, and / or posterior pleural cavity may be accessed. The size of the incision may be set to allow insertion of a delivery tool and / or a tuning tool and navigation of one or more leads 10. In some examples, more than one incision may be formed to accommodate one or more leads 10. For example, a first incision may be formed to deliver a first lead (such as lead 10a), and a second incision may be formed to deliver a second lead (such as lead 10b).

[0080] Continue Figure 11 As an example of Figure 11 , the technique 1100 may include inserting one or more leads 10 into a patient 12 via a delivery tool (1104). The size of the delivery tool may be set to allow delivery of one or more leads 10 through the delivery tool. The elongated portion of the delivery tool may be advanced within the subxiphoid space of the patient 12. The delivery tool may assist in delivering the lead at a location near the xiphoid process and / or an intercostal location (i.e., between the ribs). A tunneling device may be used in the delivery of one or more leads 10.

[0081] Continue Figure 11 As an example of Figure 11 , the technique 1100 may include positioning one or more leads 10 at an implantation site (1106). The implantation site may include a target location for placement of one or more leads 10. A first lead (such as lead 10a) may have a first target location. In some examples, a first electrode (such as electrode 32a) may be positioned to pace the patient's RV, such as near the centroid of the right ventricle. In some examples, a second electrode (such as electrode 32b) may be positioned to pace the patient's RA, such as near the centroid of the right atrium. In some examples, a third electrode (such as electrode 32c) may be positioned to pace the patient's LV, such as near the centroid of the left ventricle. In some examples, an electrode may be positioned to pace the patient's LA, such as near the centroid of the left atrium. In some examples, the electrode may be placed in other positions relative to the centroid of the corresponding atrium or ventricle. In some examples, the first lead (such as lead 10a) may be positioned anteriorly relative to the heart. A tunneling device may guide the first lead (such as lead 10a) to a position anteriorly relative to the heart. A second lead (such as lead 10b) may have a second target location. In some examples, the second lead (such as lead 10b) may be positioned posteriorly relative to the heart. A tunneling device may guide the second lead (such as lead 10b) to a position posteriorly relative to the heart. The technique 1100 may include coupling one or more leads to an IMD (1108). In some examples, the IMD may be an ICD. The technique 1100 may include configuring the IMD to deliver therapy, such as cardiac resynchronization therapy (CRT) (1110).

[0082] Although the above-described devices, systems, and methods relate to cardiac pacing and sensing, they can also be used for other applications, such as respiratory monitoring. For example, placing a device in the intrapleural space can be used to monitor symptoms of certain respiratory conditions, including but not limited to diabetes, chronic obstructive pulmonary disease (COPD), sleep apnea, and heart failure. Sensors on the distal portion of the lead can be added, modified, or otherwise configured for certain respiratory conditions. Such sensors can include but are not limited to pressure sensors, glucose sensors, electrodes that measure impedance, accelerometers that detect physical displacement, and microphones that detect acoustics. Respiratory monitoring for diabetes can include monitoring blood glucose levels as a proxy for lung function, and monitoring Kussmaul respirations, which are characterized by deep, rapid, and labored breathing, as present in diabetic ketoacidosis. Respiratory monitoring for sleep apnea can include detecting and monitoring the effectiveness of treatment, which can include continuous positive airway pressure (CPAP) treatment or hypoglossal nerve stimulation. Respiratory monitoring for heart failure can include monitoring pulmonary edema and / or Cheyne-Stokes respirations. Respiratory monitoring can also improve the sensitivity and specificity of ventricular tachycardia and ventricular fibrillation (VT / VF) monitoring, as shortness of breath or cessation of breathing can confirm traditional VT / VF monitoring methods. Intrapleural placement of the monitoring device can also be used to detect heart sounds via an acoustic sensor, which is used to monitor cardiac function and detect valvular disease.

[0083] Placement of the respiratory monitoring device can use the same or substantially the same techniques as discussed above. Electrodes (including pacing / sensing electrodes) discussed above can be modified to monitor the respiratory conditions discussed above. For example, the position and orientation of sensors on the lead can be configured to monitor respiratory conditions. For respiratory monitoring, one or more respiratory monitoring devices can be placed in the right, left, or both pleural cavities. Placement of such respiratory monitoring devices can be configured for a given respiratory monitoring application. For example, the orientation of such respiratory monitoring devices can be configured for a given respiratory monitoring application. For example, the device can be placed vertically, horizontally, or in any combination of vertical and horizontal orientations to achieve the desired result. The device can include an implantable medical device coupled to one or more leads configured to monitor one or more respiratory parameters, and a leadless monitoring device configured to monitor one or more respiratory parameters.

[0084] In other examples, placing the device in various subxiphoid or intrapleural spaces can enable atrial fibrillation (AF) monitoring. Depending on the positioning of one or more devices configured to monitor AF, AF monitoring can be performed independently from the R wave, or from the R wave with P wave confirmation. The P wave signal can be observed when the monitoring device is placed above the atrial contour.

[0085] Clause 1. A system, the system comprising: one or more leads, the one or more leads including a plurality of electrodes, wherein the one or more leads are configured to position the plurality of electrodes at a plurality of epicardial locations to deliver cardiac pacing to the right atrium (RA), right ventricle (RV), and left ventricle (LV) of a patient's heart; and an implantable medical device (IMD) coupled to the one or more leads, wherein the IMD device is configured to deliver the cardiac pacing via the plurality of electrodes.

[0086] Clause 2. The system according to Clause 1, wherein the one or more leads include: a first lead configured to position a first subset of the plurality of electrodes to deliver cardiac pacing to the RA and the RV; and a second lead configured to position a second subset of the plurality of electrodes to deliver cardiac pacing to the LV.

[0087] Clause 3. The system according to Clause 2, wherein the first lead is configured to be positioned in the anterior mediastinum of the patient.

[0088] Clause 4. The system according to Clause 2 or 3, wherein the second lead is configured to be positioned in the posterior mediastinum of the patient.

[0089] Clause 5. The system according to any one of Clauses 2 to 4, wherein the first lead and the second lead are configured to share a common entry point into the mediastinum of the patient.

[0090] Clause 6. The system according to Clause 2, wherein the first lead is configured to be positioned in the pleural cavity of the patient.

[0091] Clause 7. The system according to Clause 2 or 6, wherein the second lead is configured to be positioned in the pleural cavity of the patient.

[0092] Clause 8. The system according to Clause 2 or any one of Clauses 6 to 7, wherein the first lead is configured to be positioned in the right pleural cavity and the second lead is configured to be positioned in the left pleural cavity.

[0093] Clause 9. The system according to Clause 2 or any one of Clauses 6 to 7, wherein the first lead is configured to be positioned in the left pleural cavity and the second lead is configured to be positioned in the right pleural cavity.

[0094] Clause 10. The system according to any one or more of Clauses 6 to 9, wherein the first lead and the second lead are configured to share a common entry point into the pleural cavity of the patient.

[0095] Clause 11. The system according to any one or more of Clauses 2 to 10, wherein the first lead is configured to be positioned substantially perpendicular to the second lead.

[0096] Clause 12. A system comprising: one or more leads including a plurality of electrodes, wherein the one or more leads are configured to position the plurality of electrodes at a plurality of epicardial locations to deliver cardiac pacing to a first subset of the right atrium (RA), right ventricle (RV), and left ventricle (LV) of a patient's heart; an implantable medical device (IMD) coupled to the one or more leads, wherein the IMD is configured to deliver the cardiac pacing via the plurality of electrodes; and one or more leadless pacing devices configured to deliver cardiac pacing to a second subset of the RA, the RV, and the LV.

[0097] Clause 13. The system according to Clause 12, wherein the one or more leadless pacing devices are configured to be positioned in the mediastinum of the patient.

[0098] Clause 14. The system according to Clause 12, wherein the one or more leadless pacing devices are configured to be positioned in the pleural cavity of the patient.

[0099] Clause 15. The system according to any one or more of Clauses 12 to 14, wherein the one or more leadless pacing devices are configured to be positioned substantially perpendicular to the one or more leads.

[0100] Clause 16. The system according to any one or more of Clauses 1 to 11 or 12 to 15, wherein the cardiac pacing includes cardiac resynchronization therapy (CRT).

[0101] Clause 17. The system according to any one or more of Clauses 1 to 11 or 12 to 16, wherein the plurality of electrodes includes a plurality of electrodes configured to deliver cardiac pacing, wherein the one or more leads includes one or more electrodes configured to deliver an anti-tachycardia shock, and wherein the IMD includes an implantable cardioverter defibrillator (ICD) configured to deliver the anti-tachycardia shock via the one or more electrodes configured to deliver the anti-tachycardia shock.

[0102] Clause 18. A method, the method comprising: positioning, via one or more leads including a plurality of electrodes, the plurality of electrodes to deliver cardiac pacing to a right atrium (RA), a right ventricle (RV), and a left ventricle (LV) of a patient's heart; and delivering cardiac pacing to the RA, the RV, and the LV of the patient's heart via an implantable medical device (IMD) coupled to the one or more leads and via the plurality of electrodes positioned at a plurality of epicardial locations via the one or more leads.

[0103] Clause 19. The method according to clause 18, wherein the one or more leads comprise: a first lead configured to position a first subset of the plurality of electrodes to deliver cardiac pacing to the RA and the RV; and a second lead configured to position a second subset of the plurality of electrodes to deliver cardiac pacing to the LV.

[0104] Clause 20. The method according to clause 19, wherein the first lead is configured to be positioned in the anterior mediastinum of the patient.

[0105] Clause 21. The method according to clause 19 or 20, wherein the second lead is configured to be positioned in the posterior mediastinum of the patient.

[0106] Clause 22. The method according to any one or more of clauses 19 to 21, wherein the first lead and the second lead are configured to share a common entry point into the mediastinum of the patient.

[0107] Clause 23. The method according to clause 19, wherein the first lead is configured to be positioned in the pleural cavity of the patient.

[0108] Clause 24. The method according to clause 19 or 23, wherein the second lead is configured to be positioned in the pleural cavity of the patient.

[0109] Clause 25. The method according to any one or more of clauses 19 or 23 to 24, wherein the first lead is configured to be positioned in the right pleural cavity and the second lead is configured to be positioned in the left pleural cavity.

[0110] Clause 26. The method according to any one or more of clauses 19 or 23 to 24, wherein the first lead is configured to be positioned in the left pleural cavity and the second lead is configured to be positioned in the right pleural cavity.

[0111] Clause 27. The method according to any one or more of clauses 23 to 26, wherein the first lead and the second lead are configured to share a common entry point into the pleural cavity of the patient.

[0112] Clause 28. The method according to any one or more of Clauses 19 to 27, wherein the first lead is configured to be positioned substantially perpendicular to the second lead.

[0113] Clause 29. A method, the method comprising: positioning, via one or more leads including a plurality of electrodes, the plurality of electrodes to deliver cardiac pacing to a first subset of a right atrium (RA), a right ventricle (RV), and a left ventricle (LV) of a patient's heart; delivering, via an implantable medical device (IMD) coupled to the one or more leads, cardiac pacing to the first subset of the RA, the RV, and the LV of the patient's heart via the plurality of electrodes positioned at a plurality of epicardial locations via the one or more leads; and delivering, via one or more leadless pacing devices, cardiac pacing to a second subset of the RA, the RV, and the LV of the patient's heart.

[0114] Clause 30. The method according to Clause 29, wherein the one or more leadless pacing devices are configured to be positioned in the mediastinum of the patient.

[0115] Clause 31. The method according to Clause 29, wherein the one or more leadless pacing devices are configured to be positioned in the pleural cavity of the patient.

[0116] Clause 32. The method according to any one or more of Clauses 29 to 31, wherein the one or more leadless pacing devices are configured to be positioned substantially perpendicular to the one or more leads.

[0117] Clause 33. The method according to any one or more of Clauses 18 to 28 or 29 to 32, wherein the cardiac pacing includes cardiac resynchronization therapy (CRT).

[0118] Clause 34. The method according to any one or more of Clauses 18 to 28 or 29 to 33, wherein the plurality of electrodes includes a plurality of electrodes configured to deliver cardiac pacing, wherein the one or more leads includes one or more electrodes configured to deliver an anti-tachycardia shock, and wherein the IMD includes an implantable cardioverter defibrillator (ICD) configured to deliver the anti-tachycardia shock via the one or more electrodes configured to deliver the anti-tachycardia shock.

[0119] Clause 35. A system, the system comprising: a plurality of leadless pacing devices configured to be positioned in a plurality of epicardial locations and configured to pace a right atrium (RA), a right ventricle (RV), and a left ventricle (LV) of a patient's heart.

[0120] Clause 36. The system according to Clause 35, wherein the plurality of leadless pacing devices includes: a first subset of the plurality of leadless pacing devices configured to deliver cardiac pacing to the RA and RV; and a second subset of the plurality of leadless pacing devices configured to deliver cardiac pacing to the LV.

[0121] Clause 37. The system according to Clause 36, wherein the first subset of the plurality of leadless pacing devices is configured to be positioned in the anterior mediastinum of the patient.

[0122] Clause 38. The system according to Clause 36 or 37, wherein the second subset of the plurality of leadless pacing devices is configured to be positioned in the posterior mediastinum of the patient.

[0123] Clause 39. The system according to Clause 36, wherein the first subset of the plurality of leadless pacing devices is configured to be positioned in the pleural cavity of the patient.

[0124] Clause 40. The system according to any one or more of Clauses 36 or 39, wherein the second subset of the plurality of leadless pacing devices is configured to be positioned in the pleural cavity of the patient.

[0125] Clause 41. The system according to Clause 36, wherein the first subset of the plurality of leadless pacing devices is configured to be positioned in the right pleural cavity and the second subset of the plurality of leadless pacing devices is configured to be positioned in the left pleural cavity.

[0126] Clause 42. The system according to Clause 36, wherein the first subset of the plurality of leadless pacing devices is configured to be positioned in the left pleural cavity and the second subset of the plurality of leadless pacing devices is configured to be positioned in the right pleural cavity.

[0127] Clause 43. The system according to any one or more of Clauses 35 to 42, wherein the cardiac pacing includes cardiac resynchronization therapy (CRT).

[0128] Clause 44. A system, the system comprising: one or more extracardiac leads, the one or more extracardiac leads including a plurality of electrodes, wherein the one or more leads include: a first extracardiac lead configured to position a first subset of the plurality of electrodes to deliver cardiac pacing to the right atrium (RA) and right ventricle (RV) of a patient's heart; and a second extracardiac lead configured to position a second subset of the plurality of electrodes to deliver cardiac pacing to the left ventricle (LV), wherein the plurality of electrodes include a plurality of electrodes configured to deliver cardiac pacing, wherein the one or more leads include one or more electrodes configured to deliver antitachycardia shocks; and an implantable medical device (IMD) coupled to the one or more leads, wherein the IMD is configured to deliver the cardiac pacing via the plurality of electrodes configured to deliver cardiac pacing and / or deliver the antitachycardia shock via the one or more electrodes configured to deliver antitachycardia shocks, wherein the first lead is configured to be positioned anteriorly relative to the patient's heart, and the second lead is configured to be positioned posteriorly relative to the patient's heart.

[0129] Those skilled in the art will appreciate that the present application is not limited to what has been specifically shown and described above. Further, unless stated to the contrary above, it should be noted that all of the drawings are not drawn to scale. Without departing from the scope and spirit of the present application, various modifications and variations are possible in light of the above teachings, and the scope and spirit of the present application are defined only by the appended claims.

Claims

1. A system, the system comprises: one or more leads, the one or more leads comprising a plurality of electrodes, wherein the one or more leads are configured to position the plurality of electrodes at a plurality of epicardial locations to deliver cardiac pacing to the right atrium (RA), right ventricle (RV), and left ventricle (LV) of a patient's heart; and an implantable medical device (IMD) coupled to the one or more leads, wherein the IMD device is configured to deliver the cardiac pacing via the plurality of electrodes.

2. The system according to claim 1, wherein the one or more leads comprise: a first lead configured to position a first subset of the plurality of electrodes to deliver cardiac pacing to the RA and the RV; and a second lead configured to position a second subset of the plurality of electrodes to deliver cardiac pacing to the LV.

3. The system according to claim 2, wherein the first lead is configured to be positioned in one of the patient's anterior mediastinum or the patient's pleural cavity.

4. The system according to claim 2 or 3, wherein the second lead is configured to be positioned in the patient's posterior mediastinum.

5. The system according to claim 2 or 3, wherein the second lead is configured to be positioned in the patient's pleural cavity.

6. The system according to any one of claims 2 or 5, wherein the first lead is configured to be positioned in the right pleural cavity and the second lead is configured to be positioned in the left pleural cavity.

7. The system according to any one of claims 2 or 5 to 6, wherein the first lead is configured to be positioned in the left pleural cavity and the second lead is configured to be positioned in the right pleural cavity.

8. The system according to any one or more of claims 2 to 7, wherein the first lead and the second lead are configured to share a common entry point into the patient's pleural cavity.

9. The system according to any one or more of claims 2 to 8, wherein the first lead is configured to be positioned substantially perpendicular to the second lead.

10. A system, the system comprises: one or more leads, the one or more leads comprising a plurality of electrodes, wherein the one or more leads are configured to position a plurality of electrodes at a plurality of epicardial locations to deliver cardiac pacing to a first subset of the right atrium (RA), right ventricle (RV), and left ventricle (LV) of a patient's heart; an implantable medical device (IMD) coupled to the one or more leads, wherein the IMD device is configured to deliver the cardiac pacing via the plurality of electrodes; and one or more leadless pacing devices configured to deliver cardiac pacing to a second subset of the RA, the RV, and the LV.

11. The system according to claim 10, wherein the one or more leadless pacing devices are configured to be positioned in the patient's mediastinum.

12. The system according to claim 10, wherein the one or more leadless pacing devices are configured to be positioned in the pleural cavity of the patient.

13. The system according to any one or more of claims 10 to 12, wherein the one or more leadless pacing devices are configured to be positioned substantially perpendicular to the one or more leads.

14. The system according to any one or more of claims 1 to 13, wherein the cardiac pacing includes cardiac resynchronization therapy (CRT).

15. The system according to any one or more of claims 1 to 14, wherein the plurality of electrodes includes a plurality of electrodes configured to deliver cardiac pacing, wherein the one or more leads includes one or more electrodes configured to deliver an anti-tachycardia shock, and wherein the IMD includes an implantable cardioverter defibrillator (ICD) configured to deliver the anti-tachycardia shock via the one or more electrodes configured to deliver the anti-tachycardia shock.

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